1. Field of the Invention
This invention relates to a method and apparatus for harvesting and processing head lettuce and more particularly to a method and apparatus wherein all steps are performed at or near the field in which the lettuce is grown and with sufficient promptness after picking that deterioration of the lettuce is minimized or eliminated.
2. Description of the Prior Art
The known prior art procedure for harvesting and processing lettuce involves severing lettuce heads that are growing on the field and placing the lettuce heads in a field box or bin. In the known prior art, when the bin is full it is transported to a vacuum cooler at some remote location. A plurality of field bins are loaded into a vacuum cooler at one time for batch processing so that it frequently occurs that one or more bins are retained outside the vacuum cooler for a sufficient period of time that deterioration can take place. The prior art procedure is then to transport the now relatively cool heads to a processing plant at a remote site at which the heads are inspected, shredded, treated and packaged. Because of the substantial time between severing the head from the field and shredding of the head, the outer leaves of the head typically dry out much more than the heart of the head so that either the outer leaves must be discarded or a shredded product of non-uniform character is produced.
A method for retarding further deterioration of shredded lettuce is disclosed in U.S. Pat. No. 3,849,581 (426-145). Such method however is practiced only after the delays attending the prior art procedure described above; notwithstanding the apparent efficacy of the method, it is not able to restore lettuce that has already deteriorated due to exposure.